If the filaments are broken because of any reason while irradiating electron beams onto objects being conveyed at a high speed while being sterilized, the predetermined dose of electron beams cannot be obtained and the sterilizing process becomes insufficient. Therefore, the objects, which are not subjected to a sufficient amount of sterilization during the conveyance, should be ejected from the path. As a device for detecting broken filaments, various kinds of devices have been conventionally proposed. In the electron beam radiation device disclosed in Patent Document 1, the breaks are determined by measuring the electric current flowing through a plurality of filaments to check for changes in the whole electric current. In the electron beam radiation device disclosed in Patent Document 2, the total dose of electric beams is detected.
PATENT DOCUMENT 1: Japanese Unexamined Patent Publication No. (HEI) 11-109098
PATENT DOCUMENT 2: Japanese Patent No. 4745399